Vibration Powered RF-Transponder for Sensing Low Frequency Motion Events

Vibration energy harvesting offers a pathway to developing battery-less sensing solutions to be deployed in wireless sensor network nodes. The integration of the energy harvesters require regulation by power conditioning and control circuitry that consume some of the energy generated, reducing the effective energy available for node function. By designing a unique 3D-printed plastic structure for low frequency sensitivity and mechanical switching, and a lateral PZT bimorph for capturing energy from environmental vibrations, we report a zero-power consumption RF-transponder capable of detecting and reporting motion events without a battery. We have successfully picked up wireless transmissions on an external receiver placed ~25cm away from the transponder, shaken at 0.75 g and 20 Hz. We have additionally demonstrated the ability to harvest energy from 5 Hz vibrations up to just under 150 Hz. When placed on an oil-based electric generator, which vibrates when operating, the RF-transponder has successfully picked up the differing harmonics to identify the mode of operation as the economy or regular power setting.